Lecture 8

Question 1

Pharmacodynamics

Answer 1

It’s the study of drugs and their MOA, pharmacological effects and adverse effects

Question 2

Types of drug action

Answer 2

Stimulation
Depression
Irritation
Replacement
Cytotoxic

Question 3

Stimulation

Answer 3

Some drugs act by increasing the activity of specialised cells. I.e, adrenaline stimulates the heart resulting in increased heart rate and force of contraction

Question 4

Depression

Answer 4

Some drugs act by depressing the activity of specialised cells. I.e alcohol, general anaesthetics etc, depress the CNS

Question 5

Irritation

Answer 5

Certain agents on tropical applications can cause irritation of the skin and adjacent tissues

Counterirritants are used for this such methyl salicylate

Question 6

Replacement

Answer 6

When there is deficiency of endogenous substances, it can be replaced by drugs
I.e, insulin and thyroxin

Question 7

Cytotoxic

Answer 7

Drugs are selectively toxic for the infected organism/cancer cells
I.e, Antibiotic/Anti cancer cells

Question 8

Mechanism of drug action

Answer 8

1. Non-receptor mediated
2. Receptor mediated

Question 9

Non-receptor mediated MOA

Answer 9

1. Physical actions
2. Chemical actions
3. Through enzymes
4. Through ion channels
5. Through anti body production
6. Transporters
7. Others

Question 10

Physical actions

Answer 10

1. Osmosis
   Some drugs act by exerting osmotic effects
   I.e; 20% mannitol cerebral oedema and acute congestive glaucoma
2. Adsorption
   Activated charcoal adsorbs toxins therefor its used in treatment of drug poisoning
3. Demulcent
   Cough syrup produces a soothing effect in pharyngitis by coating the mucosa
4. Radioactivity
   Radioactive isotopes emit rays and destroys tissues. 131I is used in hyperthyroidism

Question 11

Chemical actions

Answer 11

1. Antacids
   Antacids are weak bases, hence they neutralise the acidity in stomach during peptic ulcer
2. Metals
   Like copper, iron mercury etc are eliminated from the body by chelating agents which trap in them in their ring structure and form water soluble complexes and are removed from the body.
   I.e: dimercaprol; arsenic poisoning
   Desferrioxamine; iron poisoning
   D pencillamine; copper poisoning

Question 12

Enzyme Action

Answer 12

Some drugs either induce or inhibit the enzyme activity
I.e, ACE inhibitors such as captopril are used in t/m of hypertension, congestive cardiac failure

Question 13

Ion channels

Answer 13

Some drugs directly bind to the ion channels and alter the flow of ions.
I.e, local anaesthetics blocks sodium ion channels in neuronal membrane to produce local anaesthesia

Question 14

Transporters

Answer 14

Some drugs produce their effect by binding to the transporters
I.e, SSRI bind to the 5 HT transporters which blocks the 5 HT reuptake to the neurons to give anti depressants effect.

Question 15

Antibody production

Answer 15

Vaccine produced their effect by stimulating the production of anti bodies
I.E vaccines for T.B and polio virus

Question 16

Others

Answer 16

Anticancer drugs like cyclophosphamide produce their effect by binding to the nucleic acids

Question 17

Receptor mediated MOA

Answer 17

Agonists:
Adrenaline and morphine
Antagonist:
Atropine and naloxone
Partial agonist:
Pindolol
Reverse agonists
- benzodiazepine (agonist) anti anxiety and anti convulsant
-b carbolines (inverse agonist) anxiety and convulsions